Jordan and E^^ermann. — Fishes of JSTorth America. 463 



very blunt aud decnrved ; greatest depth of head equal to its length less 

 the opercle. Mouth low, the suout but little projecting, nuixillary reach- 

 ing eye in larger specimens, further in the smaller ones; supplemental 

 bone a crescent; gill rakers much as in Corcgoiius wiUiaiusotii ; scales 

 largo. Dull silvery. Head waters of the Columbia River. A small 

 species, not exceeding 8 inches in length, closely related to CoretjomiH 

 wilUamsoni, but with larger scales. (Named for Dr. John Merle Coulter, 

 the well-known botanist.) 



Voreyoiiiis coullerii, Eigenmann &, Kirenmann, American Naturalist, November, 1892, 961, 

 Kicking Horse River, at Field, British Columbia, one of the head streams of the 

 Columbia lUver. (Type, No. 44870. Coll. Eigeumaun.) 



756. C0RE({0NIIS WILLIAMSONI, Girard. 



(Rocky Mountain Wiutefisu ; "Mountain HEiiiuNa.") 

 Head 4^ to 5 ; depth 4 to 5 ; eye 4f . D. 11 to 14 ; A. 11 to 13 ; scales 8 to 

 10-83 to 87-7 to 10. Body oblong, rather deeper than in Corer/oum quadri- 

 lateralis, but little compressed. Head shortish, conic, the profile more 

 abruptly decurved than in the other species. Snout compressed and 

 somewhat pointed at tip, which is entirely below the level of the eye ; pre- 

 orbital broad, f width of eye. Maxillary short and very broad, reaching 

 just about to the anterior margin of eye ; therefore, apparently longer 

 than in related species, owing to the shortness of the snout ; supple- 

 mental bone narrow ; maxillary contained 4 times in the length of the 

 head; mandible 3 times. Pectoral It in head; ventral Ig ; longest dorsal 

 ray 1^. Snout in the males produced, jiig-like, in the breeding season. 

 Adipose fin very large, extending behind anal. Gill rakers short and 

 thick, shorter than pupil, about 9 + 15. Color bluish above, sides silvery ; 

 breeding males with the under parts white ; all the fins tipped with black, 

 caudal and adipose fins steel-blue. Scales on sides strongly tuberculate 

 in breeding males. Length about a foot. Clear streams from the 

 Rocky Mountains to the Pacific, the easternmost records being from Chief 

 Mountain Lake at the head of the Saskatchewan in Montana (as type of 

 Corcfjonus couesii) ; abundant in the Great Basin, and northwestward on 

 both sides of the Cascade Range ; found more often in clear brooks and 

 rivers than in lakes. It readily takes the fly aud is an excellent food- 

 fish. (Named for Lieut. R. S. Williamson, in charge of one division of 

 the United States Pacific Railroad exj)loratiou8.) 



Coregoims uHlUamsoni, GiRARD, Troc. Ac. Nat. .Sci. Phila., 1850, 136, Des Chutes River, Ore- 

 gon ; GliNTHER, Cat., VI, 187, 1806 ; Jordan & Gilbert, Synopsis, 297, 1883 ; B. .\. Bean, 

 in Gilbert & Evermann, Bull. U. S. Fish Comm., xiv, 1894, 55, pi. ix, fig. 3. 



Chregouus coucsii, Milner, Kept. U. S. Fish Comm. for 1872-73 (1874), 88, Chief Mountain 

 Lake, Montana ; (Type, No. 14140. Coll. Coues) ; Jordan & Gilbert, Synopsis, 297, 1883. 



Prosopium couefii, Milner, in Jordan, Man. Vert., Ed. 2, 362, 1878. 



Represented in the Madison and Yellowstone rivers and other tribu- 

 taries of the Upper Missouri by 



756a. COREGOXUS WILLIAMSONI CISMONTAXUS, Jordan. 



Slenderer, with lower fins. Head 5 in length ; depth 5 to 5J ; pectoral 

 H in head ; ventral 1* ; longest dorsal ray 1^. Scales 90. Otherwise like 

 the typical form, {cismoidanus, this side of the mountains.) 



